This is a simple question with a somewhat complicated, but very interesting answer. The simple answer is that each pound of reasonably dry wood contains about 6,000 BTUs of heat, or energy. If you want the more complex answer, take a look at this article by from the Masonry Heater Association website. . . .
This photo-essay documents about 2 days of experimentation that resulted in a pretty stupendous new variation on Max's "Cabin Stove." The overall footprint of the stove determined the firebox size, and the geometry resulted in a rectangular heat riser that took hot gasses from a vertical throat in the corner of the firebox -- unconventional, but it worked amazingly well. More to come! (Ed. Note: This stove, like so many others, is merely one more in a long line of innovations and adaptations, all based on the same basic principles: burn the fuel fast, hot, & clean, and extract and store as . . .
Important update! This article still serves as an important archive piece in the design development. The most current Cabin Stove documentation is available at The Cabin Stove Page. What is the Cabin Stove? The Cabin Stove is a compact wood-burning stove for heating and cooking. It uses a mix of clean, efficient combustion, and heat exchange strategies, which provide both immediate heat via the cooktop as well stored heat through the channels inside the brick work. Effectively, it converts wood into warmth and good food. This cookstove is a hybrid between rocket mass heater and . . .